The comparison with thermal models is shown in more detail in
Fig. REF  for the 0–10% centrality class.
These calculations have been performed using the grand-canonical
formulation of both THERMUS [1]} and the
GSI-Heidelberg model [2]}. This approach is appropriate
for the ratios shown here, as no strange quarks are involved. Details
can be found in [3]}, [2]}. These
ratios are monotonically increasing with \(T_{\rm chem}\)  reflecting
the dependence with \(\exp (-\Delta m/ T_{\rm chem})\)  where \(\Delta m\)  corresponds to the mass difference of the particles under
study.
<FIGURE>